Hydraulic servo-steering system



Aug. 28, 1951 QNDE HYDRAULIC SERVO-STEERING SYSTEM S'Sheets-Sheet 1 WM a a w EE Aug. 28, 1951 M. A. ONDE HYDRAULIC SERVO-STEERING SYSTEM 5 SheetsHSheet 2 Filed Dec. 31, 1947 z a e7z kl' WarceZ A Ozae E i I n y' Aug. 28, 1951 M. A. ONDE HYDRAULIQ SERVO-STEERING syswm 3 Sheets-Sheet 3 Zgae/z. 5 I W eZ 4. 0zzd Filed Dec. 31, 1947 Patented Aug. 28, 1951 HYDRAULIC SERVO-STEERING SYSTEM Marcel Auguste Onde, Paris, France, assignor of one-half to Jacques Guerin, Paris, France Application December 31, 1947, Serial No. 795,035 In France December 8, 1945 Section 1, Public Law 690, August 8, 1946 Patent expires December 8, 1965 Claims. (01. lac-79.2)

This invention relates to power steering mechanism and more particularly to a fluid operated system that is directly connected to the vehicle steering bar.

The ever-increasing tonnage and speed of modern vehicles imposes undue fatigue on the drivers in the handling of the steering wheel and, therefore, a. reduction in their potential of energy and reflexes. In order to avoid this fatigue, it has been proposed to increase the reduction ratio of the steering gears, but this gain automatically involves a longer time of handling and, therefore, an undue slowing down for turns, whence a loss of time and power. For securitys sake, in order to avoid undue fatigue on the one hand, and loss of time on the other hand, it is advisable not to increase the reduction ratio unduly but to leave the initiative and the control of actuation to the driver and to impose the work on the machine.

In order to relieve the driver, various types of servo-steering devices have already been proposed. The existing devices, however, comprise as many different types of levers and countergears as there are types of vehicles; furthermore, these levers must form hinged parallelograms which are rather complex and in which the play of the rather numerous joints interferes with the operation of the apparatus.

The present invention remedies these drawbacks. It has for its object to provide a servosteering device for vehicles in which the steering bar comprises a casing in which is placed, between two resilient stops, a ball at the end of an arm pivotally mounted around a shaft that is subject to the action of the steering column, one of said stops acting upon a rod controlling, through the medium of a pivoting arm, a distributor of fluid under pressure which feeds a servomotor for imparting a movement to the steering bar in one direction or the other, according to the distribution circuit established by the distributor.

The novel features that are considered characteristic of the invention are set forth with particularly in the appended claims. The invention itself, however, both as to its organization and its method of operation, together with additional objects and advantages thereof, will best be understood from the following description of specific embodiments when read in connection.

with the accompanying drawings, wherein like reference characters indicate like parts throughout the several figures and in which:

Fig. 1 is a. diagrammatic cross-sectional view taken longitudinally along the axis of a servosteering apparatus in accordance with the present invention;

Fig. 2 is an enlarged diagrammatic cross-sectional view of the distributor system shown in Fig. 1 and in position for supplying fluid to oper- Fig. 5 is a diagrammatic cross-sectional view of a modification of the servo-steering apparatus; and

Fig. 6 is a fragmentary top plan view of the modified apparatus, parts being broken away to illustrate the control lever system of the distributor.

The mechanism shown in the drawings essentially comprises the usual steering wheel column carrying a worm-l on its lower end'which is in mesh with a worm gear sector 2 that is pivotally supported by a shaft 3. A counter-arm-4 is fixed to the shaft 3 and carries a ball 4 on its lower end. This ball 4' nests between two abutments 5 and 6 which are slidably mounted within a casing 9 that is rigid with the steering bar 9.

A rod- I0 is rigidly secured at one end to the abutment 6 and is connected at its other end with a lever I 2 by a pivot II. The lever I2 is pivotally mounted by a pivot I3- to a housing 14 which is shown plugged and joined in and closing one end of casing 9, rigid with the casing 9 and the steering bar 9'. Y

Theupper end of the lever I2 is positioned between two hollow tubular piston members 19 and 20 which respectively control two double valves I5l6-and l1l8.' The piston members l9 and 28' are sealed by packings 59 and and have passages 52 and '53 therethrough so that they also form valves. The double valves are biased against their seats by springs 2| and 22.

The servo-motor comprises a cylinder 23, within which the double stroke piston 24 is slidably mounted for operative movement in both directions and sealed by packings 25 and- 26. The cylinder 23 is pivotally connected by and adapted to swing about a ball pivot 30 with a bracket 3| that is fixed to the veehicle frame. The cylinder can be secured through a suitable so-called hollow rod device. The piston rod 21, which is sealed where it passes through the cylinder by the packing 28, is connected with a ball 29 having a stem or shank fixed to the end of the housin or distribution box l4.

According to the modification shown in Figs.

5 and 6 the pivot II actuates a control lever 34 which is pivotally mounted by a pivot 33 in a control box 42. At its upper end, the lever 34 carries a pin 35 to which a flexible cable 39. is connected and'secured by a part 32. This. cable 39 extends from the control box 42 and passes through an incompressible flexible sheath 38, one end of which is secured to the box 42 by an adjustable member 36 and the other end of which is secured to the distributor 46 by an adjustable member 31. The cable 39 extends into the distributor 46 and is connected with a lever 40 by a pin M and a cooperating part 43. Thecable 39 is tensioned by a spring 44 of selected resiliency. The lever 49 is pivotally mounted on the pivot 45 and is positioned between the piston membersv I9 and 20 as previously described, the remainder of the device being common with the arrangement of Fig. 1.

The operating fluid is compressed air, preferably, which is supplied through the piping 4-!- into the chambers 48 and 49 containing the flap valves I 5 and IB. When the driver actuates the steering Wheel so that the counter-arm 4- moves towards the left (Figs. 1 and 5) thespring 'I'will becompressed while the spring 8 will expand. The abutment 6 will movetowards the left while carrying with it the lever [2 (Fig. 1') or 34-49 (Fig. 5) which will, in turn, drive the piston valve member I9 (Fig; 2), thus insuring-the contact of' the latter with thefiap valve I6, while the flap valve I5 will leave its seat to permit the compressed air to flow from the chamber 48 into the chamber 59. The air will flow fromthe chamberEIi-through the flexible piping 54 (Fig.

l) or passage 54' (Fig. 5) into the chamber 55 of the servo-motor cylinder 23, whence the com pressed air will act upon the corresponding face ofthepiston- 24a The air pressure will, therefore, movethe piston 24 towards the left and push on the steering bar 9' through the medium of'its rod 21- and the ball 29.

' If the driver holds the wheel fast in this position the piston will push the steering bar 9 until the re-establishment of the initial position of the lever I2" or 34-49 and the valve I5. Asa matter of'fact', if thecounter-arm 4 is held fast while the piston pushes on the steering bar, one will obtain a relative movement between the abutment system 6 and the lever I2 or 34-49 on the one hand, and the steering bar 9- and the distributor I4 (Fig. l) or'control box 42 (Fig. 5') on the other hand. In this movement, since the lever I2 or 34-49 is mounted on the pivot II,

which has become stationary while the pivot I3 '(Fig; 1) or 33 (Fig. 5)' moving with housing I4 or 42 actuates the lever I2 or 34-40, this latter ceases to push on the piston valve member I 9 andthe flap valve I5 closes and thus interrupts the supply of air to the piston chamber 55' so that the piston 24-is no longer moved towards the left. If it should continue to move through the expansion of the compressed air, the flap valve I6 will break the contact with the piston valve member I9 and allow the compressed air to pass from the chamber 5Ilthrough the passage 52 of the piston valve member I9 into the atmosphere through the opening 58, whereby the chamber 55 would be connected with the atmosphere through the flexible piping 54 or-passage 54 and the'chamber 59, as shown in Fig. 3'. The piston will, therefore, be immediately stopped in its action.

The actuation of the steering in the reverse direction causes an identical operation for the right part of the distributor (Fig. 4) and the left part of the cylinder. The operating fluid or compressed air is supplied through piping 41 to chamber 49 containing flap valve I8, sothat when the driver turns the steering wheel to move counter-arm 4 to the right (Figs 1, 4 and 5) the spring 8 will be compressed while the spring I will expand. The abutment 5 moves toward the right to move lever I2 or 34-4B and piston valve 29 with it so that the latter will contact flap, valve II, while valve I8 leaves its seat to permit the compressed air to flow from chamber 49 into chamber 5] and from the latter through piping 56 or passage 56 into chamber 57 of cylinder 23 to act upon and move piston 24 towards the right, and pull bar 9 through rod 21 and ball pivot 29. If the driver holds the Wheel fast, the piston 24 will pull bar 9 until re-establishment of the initialposition of lever [2 or 34'-49 and valve I8. If counter arm 4 15 held fast while the piston pulls on the steering bar 9', there will be a relative movement between the abutment 5 and lever I2 or 3449 on the one hand, and the steering bar 9, casing 9 and distributor I4 or control box 42 on the other hand.

Since lever I2 or 34-49 is mounted on pivot II, which is stationary, while pivot I 3-or 33 actuates lever I2 or 3440, the latter ceases to push piston valve member 29 and flap valve IBcloses and thus interrupts-the air supply to piston chamber 51 so that piston 24 no longer moves to the right. If it continues to move by expansion of the compressed air, flap valve Il will break contact w-ith piston valve member 29 and allow compressed air to pass from chamber 5i through passage 53 of member 28 into the atmosphere through opening 58 whereby chamber 5I is connected with the atmosphere through'piping 58 orpassage 56 and chamber 51 to stop the action of piston 24;

The modification of Figs. 5 and 6. differs; as regards the operation solely through the remote control device in the control box; 42; acting by means of the cable 39. The lever 3-.4'acts; thereforauponthe cable 39 which thus communicates the displacement to the lever is. This latter actuates the distributor in: the'same manner as the-lever I2 in Fig. 1'. The particularity of this cable system is due to the impossibility for a cable to work under compression, since it, is flexible. The cable Works, therefore, between two springs 5 and which must be calculated so that they can insure the actuation of the distributor through their own action. The spring 44. can workv differentially or additionally in stress with the springs according to whetherthe cable is mounted on one side of the control box- 42 or on the other. It is also possible to, use, two. cables instead of only one and to omit the spring. 44. The spring 44?- can be replaced by small fluid cylinder arranged to pull onythe cable. j It. is obvious, moreover, that the invention is described and shown only by way of illustration and-not by way of a limitative example and that modifications can be in the details of the apparatuswithout departing from itsscope and spirit.

The driver always actuates the steering wheel, the movement of which is transmitted to the steering bar .9 and vehicle wheels through the cuedium of a ball. Applied against the latter are two abutments, each possessing an application spring which presses on the steering bar with it other extremity.

These springs are calculatedso that a normal stress on the steering wheel can compress them untilthe abutment directly bears-on the steering bar. It is only at this moment that the direct actuation of the steering will begin, which possibility will remedy any failure of the servosteering system. If one of the abutments is fixed with a rod actuating a small amplifying lever, the control action is effected beforethe abutment comes into contact with the steering bar.

This amplifying lever will actuate an electric or mechanical contacting distributor which re leases a driving power which is applied in the direction required by the actuation of the steering wheel.

In the described apparatus a servo-motor is employed as a prime mover, the driving fluid of which is compressed air, the distributor being a flat slide valve or a cylindrical valve or a flap valve system of any kind.

The amplifying lever, therefore, actuates the distributor, the latter admitting compressed air into the cylinder on the one side of the piston or on the other. The action of the piston is exerted on the end of the steering bar through a linked but rigid connection between the piston and steering bar. Besides its driving function, the cylinder serves, therefore, effectively, as a damper for damping the oscillations of the steering due to any obstacles on the road.

Although certain specific embodiments of the invention have been shown and described, it is obvious that many modifications thereof are possible. The invention, therefore, is not to be restricted except in so far as is necessitated by the prior art and by the spirit of the appended claims.

I claim:

'1. A servo-steering device for vehicles, comprisinga steering bar, a casing rigid and in line with said bar, two resilient abutments in said casing, a steering column, an arm pivotally mounted around a shaft rotatably controlled from said column through a suitable gear, a ball provided at the end of said arm and positioned in said casing between and in contact with said abutments, a rod rigidly connected to one abutment in the casing, an arm pivoted in and to said casing to move with the latter and the bar, and pivoted between its ends to said rod, a distributor for a fluid under pressure comprising two opposed chambers, a pair of seats in each chamber, a pair of valve members rigidly connected by a rod in each chamber, a spring biasing said valve members against the two seats, a fluid inlet to each chamber, a fluid delivery from each chamber, a fluid supply connected to the two inlets of said distributor, two hollow plungers open at their outer ends and closed at their inner ends with the free end of the second arm therebetween in contact therewith and provided with outlet passages near their closed ends leading to the atmosphere, the chambers each having spaced apertured walls, the outer of which form seats for the outer valves and the inner of which slidably receive the plungers in air-tight connection therewith, the open ends forming seats for the inner valves, said outer valves adapted to simultaneously close while the inner valves are open, or the opposite outer and inner valves of the pairs adapted to independently close while the other valves of said pairs are open and vice versa respectively, when the arm is moved in opposite directions, a servomotor comprising a cylinder, one head of which is pivotally connected to a part of the vehicle body, a piston in said cylinder, a piston rod on the piston passing through the other cylinder head and pivotally connected to the end of the casing opposite the steering bar in-line therewith, and fluid passages between the two deliveries of the distributor and two chambers of said cylinder on either side of said piston.

' 2. A servo-steering device for vehicles, comprising a steering bar, a casing integral with said bar, two resilient abutments in said casing, a steering column, an arm pivotally mounted around a shaft rotatably controlled from said column through a suitable gear, a ball provided at the end of said arm and positioned in said casing between said abutments, a rod rigidly connected to one abutment, a pivoting arm arranged in said bar and controlled by said rod, a distributor for a fluid under pressure rigid with said steering bar through said casing, comprising two opposed chambers, two seats in each chamber, two valve members rigidly connected by a rod in each chamber, a spring pushing said valve members against the two seats, a fluid inlet to each chamber, a fluid delivery from each chamber, a servomotor comprising a cylinder, one head of which is connected to a part of the vehicle body, a piston in said cylinder, a rod secured to said piston passing through the other cylinder head and pivotally connected to the end of the steering bar, two

plungers contacting with the end of the pivoting arm arranged in the steering bar to be moved by the latter and operating the valve members to cause fluid under pressure to pass to a chamber of the servo-motor, a fluid supply connected to the two inlets of said distributor, and a pipe connecting said fluid deliveries to a chamber of the servo-motor at opposite sides of th piston therein,

3. A servo-steering device for vehicles, comprising a steering bar, a casing rigid and in line with said bar, two abutments in said casing, a steering column, a shaft rotatably controlled from said column through a suitable worm gear, an arm fixed to the shaft and having a ball at the end thereof positioned in said casing between said abutments, a single spring around each abutment in said casing urging said abutments in constant contact with said ball, a rod rigidly connected to one abutment and extending rearwardly therefrom to slide in the casing in line therewith, a second arm pivoted at one end in the casing to move therewith and the bar, and pivoted between its ends to the rear end of the rod, a distributor for fluid under pressure rigid with said casing and bar and comprising two opposed divided chambers, a hollow plunger closed at its inner end,

movable in sealed connection through the inner end of each divided chamber, open at its outer end to form a seat, and provided with an opening through its wall inwardly of the inner end of each divided chamber and open to the atmosphere, a pair of rigidly connected valve members in each of said divided chambers and seating inwardly against the dividing wall thereof and the outer end of a plunger, a spring biasing said pair of valve members against said seats, the free end of the second arm being constantly engaged by the closed ends of the plungers to move the latter in opposite directions, outlets from the inner chambers controlled by the second arm and pairs of valves, a fluid supply connected to two inlets of said chambers, a servo-motor comprising a cylinder, one head of which is pivotally connected to a part of the automobile body, a piston in said cylinder, a piston rod rigidly extending from said piston through the other cylinder head and pivotally connected to the inner end of the casing, and

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pipes. connecting the outlets and two chambers of the cylinder on either sideof the-piston.

4. A servo-steering device for vehicles, comprising a steering bar, a casing rigid and inv line with said bar, two abutments in said casing, a steering column, a shaft rotatably controlled from said column through a suitable worm gear, an arm fixed to the shaft and having a ball at the end thereof positioned in saidcasing between said abutments, a single spring around each abutment in said casing urging said abutments in constant contact with said ball, a rod rigidly connected to one abutment and extending rearwardly therefrom to slide in the casing in line therewith, a secondarm pivoted at one end in th casing to move therewith and the bar, and pivoted between its ends to the rear end of the rod, a servo-motor comprising a cylinder, one head of which ispivotally connected to apart of the automobile body, a piston in said cylinder, a piston rod rigidly extending from said piston through the other cylinder head and pivotally' connected to the end of the casing remote from the steeering bar, a distributor rigid with said servo-motor cylinder and comprising two opposed divided chambers, a hollow plunger closed at its inner end, movable in sealed connection through the inner end of each divided chamber, open at its outer end. to. form a seat and provided with an opening through its wall inwardly of the inner end of each divided chamber and open to the atmosphere, a pair of rigidly connected valve members in each of said divided chambers and seating inwardly against the dividing wall thereof and the outer. end of'a plunger, a spring biasing said pair of valv members against said seats, a third arm pivoted in the distributor and extending between and constantly engaged by the closed ends of the plungers to move the latter in opposite directions, a fluid inlet to each chamber, a fluid outlet-from eacnchamber, fluid passages between the two outlets of the distributor and twochambers of the cylinder on opposite sides of the piston, a cable and sheath connection between the free end of the-second arm and the free end of the third arm to cause them to move together, and means biasing the third arm and cable under tension to an intermediate position.

5. A servo-steering device for vehicles, comprising a steering bar, a casing rigid and in line with said bar, two abutments in said casing, a steering column, a shaft rotatably controlled from said column through a suitable worm gear, an arm fixed to the shaft and having a ball atthe end thereof positioned in said casing between said abntments, asinglespring aroundeach abutment insaid casing urging said'abutments in constant contact withsaid ball, a rodrigidly connected to one'abutment' and extending rearwardly therefrom to slide inthe casing in line therewith, a housing, a second arm pivoted at one end in the housing and operatively connected to the rear end of the rod to move therewith simultaneously with or independently of the casing and bar, a distributor for fluid under pressure comprising two opposed divided chambers, a hollow plunger closedat its inner end, movable in sealedconnection through the inner end of each divided chamber, open at its outer end to form a seat, and provided with an opening through its wall inwardly of the inner end of each divided chamber and open to the atmosphere, a pair of rigidly connected valve members in each of said divided chambers and seating inwardly against the dividing wall thereof and the outer end of a plunger, a spring biasing said pair of valve members against said seats, the second arm being constantly engaged by the closed ends of the plungers to movethe latter in opposite directions, outlets from the inner chambers controlled by the second arm and pairs of valves, a fluid supply connected to two inlets of said chambers, a servo-motor comprising a cylinder, one head of which is pivotally connected to a part of the automobile body, a piston in said cylinder, a piston rod rigidly extending fromsaid piston through the other cylinder head and pivotally connected to the endof the casing remote from the steering bar, and passages connecting the outlets and two chambers of the cylinder on either side of the piston.

MARCEL AUGUSTE ONDE.

REFERENCES CITED The following references are of record in the 

